Mass is the amount of matter present in a body while weight is a measure of how strongly gravity pulls on that matter. Mass is an intrinsic property of the body and remains the same wherever the body might be. Weight is a force, and force is (Mass * Acceleration). The weight of an object is its mass times the acceleration due to gravity. The weight of the body differs by place. For example, objects weigh less on the moon where gravity is lower compared to the Earth.
|Definition||Mass is the quantity of matter in a body regardless of its volume or of any forces acting on it.||Weight is a measurement of the gravitational force acting on an object.|
|Effect of gravity||Mass is always constant at any place and any time||The weight of an object depends on the gravity at that place|
|Measurement Unit||Mass is expressed in kilogram (kg), grams (g), and milligram (mg).||Weight is expressed in Newton (N)|
|Balance used for measurement||Mass is measured using a pan balance, a triple-beam balance, lever balance or electronic balance.||Weight is measured using a spring balance.|
|Type of Quantity||Scalar and base quantity||Vector and derived quantity|
Measurement of mass vs. weight
Weight is measured using a scale which effectively measures the pull on the mass exerted by the gravity of the earth. Mass of a body is measured by balancing it equally with another known amount of mass. Mass may be measured using a pan balance while Weight may be measured using a spring balance. Methods may be interchanged if gravity is known and constant, as it is on earth.
Effect of gravity of mass and weight
The weight of an object depends on the gravity at that place while Mass is always a constant at any place and any time. Eg., If an object's mass is 60 kgs, then its Weight would be 600 Newtons but when taken to the Moon, this object will have a weight of 100 newton as the gravity of the moon is 1/6th that of the Earth. But the mass of that object will remain the same.
Mass can be a constant while Weight varies.
External Factors affecting weight
Mass is an intrinsic measure of an object and hence is independent of any external factors. Weight, on the other hand, depends on the mass that is attracting it and the force with which it is being attracted.
Conversion from mass to weight
Newton's second law is used to convert between weight (force) and mass:
The equation for force is F = ma (force = mass × acceleration).
Here, F is the force due to gravity (i.e. the weight), m is the mass of the object in question, and a is the acceleration due to gravity, on Earth approximately 9.8 m/s² or 32.2 ft/s²).
In this context the same equation is often written as W = mg, with W standing for weight, and g for the acceleration due to gravity.
Relative weight on Earth, moon and other planets
The following is a list of the weights of a mass on the surface of some of the bodies in the solar system, relative to its weight on Earth:
- Weight on Mercury: 0.378
- Weight on Venus: 0.907
- Weight on Earth: 1
- Weight on Moon: 0.165
- Weight on Mars: 0.377
- Weight on Jupiter: 2.364
- Weight on Saturn: 0.910
- Weight on Uranus: 0.889
- Weight on Neptune: 1.125
Use of weight vs. mass
In the physical sciences, the terms “mass” and “weight” are rigidly defined as separate measures in order to enforce clarity and precision. In everyday use, given that all masses on Earth have weight and this relationship is usually highly proportional, weight often serves to describe both properties, its meaning being dependent upon context. For example, in commerce, the net weight of retail products actually refers to mass and is properly expressed in pounds (U.S.) or kilograms. Conversely, the load index rating on automobile tires, which specifies the maximum structural load for a tire in kilograms, refers to weight; that is, the force due to gravity.